1. Field of the Invention
This invention relates to a respiratory device and method, more particularly to an adaptor for introducing an endoscope and endotracheal tube to an anesthesia mask, for nasal or oral intubation, by way of a single stage seal, and for removal of the mask and adaptor from the endotracheal tube.
2. Description of the Prior Art
Endotracheal intubation is now the standard and accepted method for administering general anesthesia for major surgical procedures. It provides good airway control, making general anesthesia safer.
Certain patients classified as "The Difficult Intubation" present themselves from time to time. They include those with limited cervical spine mobility, poor mobility of the mandible, a receding lower jaw with obtuse mandibular angle, short muscular neck, high arched palate associated with a long narrow mouth, and protruding upper incisors. An anesthesiologist may then resort to the flexible fiberoptic scope to provide a coaxial guide for the endotracheal tube.
During this procedure one wishes to have equipment which permits easy, quick, yet gentle and controlled insertion of the fiberoptic scope, then of the endotracheal tube, with minimum break in ventilation time or loss of ventilation pressure.
The present invention satisfies that need and also permits complete removal of the mask and associated anesthesia circuit connectors from the scope and tube systems when the tube is in place for ventilating the patient.
Various devices and methods have been developed over the years to facilitate fiber optic endotracheal intubation. Many methods use a mask with an adaptor for receiving and delivering the fiberscope and endotracheal tube to the mask, and a connector on the mask or on the adaptor for delivering anesthesia to the mask.
Steps embodied in various methods for fiber optic endotracheal intubation typically include:
Method A
After inducing general anesthesia by mask, remove the mask and:
1. insert an airway for tongue control
2. insert a fiber optic scope by way of nose or mouth and optically guide the fiber optic scope into the trachea, slip an endotracheal tube which was resident over the back portion of the fiberoptic scope, in over the fiberoptic scope until it locates in the trachea, withdraw the fiber optic scope from the endotracheal tube, inflate the endotracheal tube cuff.
3. apply gas supply to the endotracheal tube
Method B
1. insert an airway
2. apply a mask having a diaphragmed opening in the mask or in an adaptor attached to the mask, and another anesthetic circuit opening.
3. attach anesthetic gas supply to the circuit opening,
4. insert an endotracheal tube containing a fiberoptic scope, through the diaphragm opening, into the mask, and optically guide the fiber optic scope by way of the nose or mouth into the trachea, follow with the endotracheal tube, moving it in over the fiberoptic scope until it locates in the trachea, withdraw the fiber optic scope from the endotracheal tube, inflate the endotracheal tube cuff.
5. apply gas supply to the endotracheal tube and disconnect anesthesia circuit from the circuit opening.
6. slide the mask and adaptor back along the endotracheal tube to remove it from the face, and hang the mask and tube clear of the immediate work area.
7-9. alternate to hanging the mask;
7. remove the gas supply from the rear end of the endotracheal tube, and remove the coupler from the endotracheal tube,
8. slip the mask and adaptor off the endotracheal tube,
9. reinstall the coupler and the gas supply.
Method C
After step 3 of method B,
4. insert a fiberoptic scope through the diaphragm opening, into the mask, and optically guide the fiber optic scope by way of the nose or mouth into the trachea, force with lubrication, an endotracheal tube which was resident over the back portion of the fiberoptic scope, through the diaphragm opening, moving it in over the fiberoptic scope until it locates in the trachea, withdraw the fiber optic scope from the endotracheal tube, inflate the endotracheal tube cuff.
5. apply gas supply to the endotracheal tube and disconnect anesthesia circuit
6. slide the mask and adaptor back along the endotracheal tube to remove it from the face, and hang the mask and tube.
7-9. The alternate to hanging the mask is the same as above.
Method "A" poses the problem of cessation of gas supply to the patient during the time span necessary for steps 1 and 2. This forces the anesthesiologist to weigh the advantage of slow and deliberate work against expediting the procedure to minimize apenia time.
Method "B" carries the possibility of loss of anesthesia gas pressure through the surrounding space space between he fiberoptic scope and the endotracheal tube during intubation of the fiberoptic scope. Seal rings in the space to reduce gas loss restrict controlled movement between the tube and scope. Removing the mask from the patient's face after intubation causes physical stress on the endotracheal gas supply system as the mask is drawn to the back end of the tube.
Method "C" maintains a gas tight seal between the diaphragm and the fiberoptic scope during intubation of the scope, but limits the diameter of the endotracheal tube with respect to the diameter of the fiber optic scope. The diaphragm opening and resiliency of the diaphragm must be selected to accommodate the two diameters. Invariably fit with the diaphragm opening negatively affects at least one of gas tight seal, feel of the procedure, and freedom to advance the tube through the diaphragm. Removing the mask from the patient is also difficult and cumbersome.
One example of a mask with an opening incorporating a seal for a tube is an anesthesia mask described in U.S. Pat. No. 2,625,155, patented by A. E. Engelder on Jan. 13, 1953. The mask permits removal of accumulated secretions from the mouth and nose of the patient by suction through a catheter without need for lifting or removing the mask. A pair of nipples are provided on the side of the mask for gas lines. Two ports, a nasal port and an oral port, each with a removable plug, are located at the front of the mask. The nasal port is located below the center line of the mask for intubation through either nostril, and the oral port is located for access by the suction catheter to the root of the tongue. Each port is supplied with a rubber ring attached to the interior of the mask to provide a leakproof seal between the catheter and the mask. The catheter therefore may be left in place continuously during anesthesia, and aspiration may be a accomplished periodically by applying suction to the catheter.
Concord/Portex Company of Keene, N.H. 03431 offers a Y adaptor which attaches to a mask at an opening located on the mask for intubation. The Swivel Adaptor with fiberoptic Bronchoscopy cap, Part No. 04-625109 has a first opening for attaching to the mask, a second opening which swivels to allow the respiratory circuit to assume a convenient angle to reduce drag and uncomfortable pressure, and a third opening with a flexible diaphragm cap having a central opening therethrough for sealingly receiving a broncho-fiberscope. U.S. Pat. No. 4,475,548, patented by Muto on Oct. 9, 1984, describes a fitting for an adaptor that attaches to the back end of an endotracheal tube. It is suited for use after intubation of the endotracheal tube is completed. The fitting delivers a fiber optic tube or a suction catheter tube by way of the adaptor to the endotracheal tube. The adaptor includes a branch opening for attachment to a respirator circuit.
In order to maintain the desired pressure in the endotracheal tube that is attached to the adaptor, the fitting has a foam rubber body which is contained in a cylindrical head that tapers to a smaller diameter at its lower end that connects to the adaptor. A closely fitting cylindrical cap having an annular top defining a small central opening, is forced down over the head until the lower portion of the cap snap-locks over a ridge on the head. The foam rubber body, having a bell shape, and a volume that is greater than the enclosure formed by the capped head, is forced to simultaneously extend somewhat up through the central opening and down into the tapered smaller diameter.
In order to form a leak proof opening for delivery of the fiber optic tube to the adaptor and on into the endotracheal tube, a knife is inserted into the central opening and driven down through the foam forming a slit therethrough for receiving the fiber optic therethrough. Because the central opening is of smaller diameter than the inner diameter of the head, the slit does extend radially completely through the foam. When the slit is cut, the pressure in the foam is partially relieved locally at the cut near the annular so that the foam is slightly dimpled where it extends through the central opening.
In operation, the fitting is lubricated with a sterile saline solution on the foam body which is preferably made from open celled foam in order to retain the lubrication for an extended period. The fitting is then inserted by its lower end into the adaptor. The assembly is then connected to the ventilator circuit by way of the adaptor connection, and to the endotracheal tube by way of the adaptor connection for that purpose.
The fiberoptic scope or suction catheter is then inserted through the slit in the foam body, down through the adaptor, and and down through the tracheal tube with a complete seal at the fitting and no damage to the surface of the delicate optical fibers or other outer surface of the scope.
Different sizes of endoscopic tubes are accommodated due to the softness of the foam, more sizes than diaphragm wall apertures could accommodate. The open celled lubricated foam eases in-feed and withdrawal of tubes, more than with collar seals.
When endwise insertion of the fiberoptic scope tube is not possible, the fitting is made in two halves which snap together around the tube by means of pins and holes in ears which extend from the fitting cavity shell halves. This fixed compression arrangement and break through the fitting shell wall can reduce seal effectiveness.
The fitting, as pointed out earlier, is designed for attachment to an endotracheal tube assembly after intubation of the endotracheal tube. It would be difficult, however to use a unit of this type for a complete procedure of fiberoptic guided, endotracheal intubation.
The fitting must be either cut to perform method B, that is accommodate an endotracheal tube containing a fiberoptic scope, or cut to perform method C, that is accommodate a fiberoptic scope, then try to force through an endotracheal tube over the scope.
Either way, the problems associated with sealing rings and with diaphragms of the earlier apparatus for performing those methods apply with this one.
One adaptor which overcomes many of the problems associated with the above ring, diaphragm, foam body and other single stage seals is described in U.S. Pat. 4,580,556, patented by Kondur on Apr. 8, 1986.
It is a two stage apparatus, comprising a housing having three openings. The first opening is for attachment to an anesthesia mask. The second opening is for attachment to an anesthesia circuit. The third opening is for for receiving a stretchable diaphragm which snaps over the third opening by a rim around the third opening.
The housing receives an endotracheal tube through a central opening in the diaphragm, for intubation of the tube by way of the first opening and mask. A solid plug is provided for sealing the central opening in the absence of the endotracheal tube. The stretchable nature of the diaphragm allows endotracheal tubes of different diameter to be inserted through the opening.
A second plug of soft material fits in the back opening of the endotracheal tube. The second plug has a central throughbore and is flexible enough to receive a fiberscope fiberoptic tube or line therethrough for intubation of the fiberoptic tube by way of the endotracheal tube.
The diaphragm seals around the endotracheal tube which is passed down through the mask, while the second plug in the back of the endotracheal tube seals around the fiberscope that is passed down through the endotracheal tube.
As discussed earlier, a resilient opening of a diaphragm or plug limits the diameter of the tube that it can receive if a combination of good seal and low resistance to movement through the opening is to be maintained. Removal of the mask from the patient after intubation is difficult and cumbersome because the diaphragm seal must be drawn back along the endotracheal tube.